Inflammatory bowel disease (IBD) is a chronic condition that causes serious complications and reduces quality of life. The emergence of anti-tumor necrosis factor (TNF)-α agents was an impactful event for the treatment of IBD [1]. Such biologic therapies have contributed to mucosal healing, prolonged remission, and improved fistula closure [2], [3], [4], [5], [6]. Infliximab (IFX), the first biologic drug for IBD, has significantly reduced the need for hospitalization and surgery [7], [8]. Although biologic agents help to improve outcomes such as remission rates and quality of life, they are less cost-effective than conventional therapies [9]. Thus, long-term use of these drugs can place a significant burden on the national health system.

Since the patent expiration of originator IFX, biosimilar products of IFX have been developed to overcome the high costs of originator IFX drugs. By definition, A biosimilar is a biological medicine highly similar to another biological medicine already approved in terms of structure, biological activity and efficacy, safety and immunogenicity profile. A biosimilar is not regarded as a generic of a biological medicine because the natural variability and more complex manufacturing of biological medicines do not allow an exact replication of the molecular micro-heterogeneity. CT-P13 (Celltrion, Inc., Incheon, Republic of Korea) was the first infliximab biosynthetic and has been approved by the European Medicines Agency (EMA) and the Food and Drug Administration (FDA). Based on randomized clinical trials for rheumatoid arthritis and ankylosing spondylitis [10], [11], CT-P13 received marketing authorization from the EMA and FDA in 2013 and 2016, respectively [12], [13]. Therefore, for other indications including IBD, it has been approved as an extrapolated indication without a clinical trial.

Since its approval, the efficacy and safety of CT-P13 for IBD have mainly been validated by studies on switching from originator to biosynthetic IFX or vice-versa [14], [15], [16], [17], [18]. In January 2017, the European Crohn’s and Colitis Organization announced that no clinically meaningful difference existed in the efficacy and safety between CT-P13 and originator IFX and that switching products was acceptable [19]. In 2019, the first prospective randomized control trial, which included 220 active bio-naïve patients with Crohn’s disease (CD), indicated the non-inferiority of CT-P13 to originator IFX [20]. Although this study included almost 30 % Asians, validation of the efficacy and safety of CT-P13 for CD patients in real-world clinical situations required more extensive evaluation in Asian patients with CD because of the rising prevalence of CD in the Asian population [21].

This study aimed to verify the efficacy and safety of biosimilar anti-TNF-α agents compared with those of originator IFX through week 54 in patients with CD who were naïve to biological therapy in a Japanese hospital-based cohort.